What is the primary function of an impeller in a boat?

The primary function of an impeller in a boat is to generate propulsion. An impeller is a rotating component within a pump, often found in jet drive systems or certain types of inboard engines. It draws in water and expels it at high velocity, creating thrust that propels the vessel forward. This mechanism is crucial for moving the boat through the water efficiently.

The other options pertain to functions not associated with an impeller. For instance, controlling sail orientation relates to sailing vessels utilizing sails for movement rather than propulsion systems like impellers. Anchoring involves securing the boat in a fixed position, which is unrelated to the propulsion system. Providing steering feedback is a function related to the steering mechanism, not the propulsion system. Thus, the ability of the impeller to create thrust distinguishes it as the correct answer in this context.